The present invention relates to artificial leather. Particularly, the invention relates to artificial leather having excellent abrasion resistance, flex durability at low temperature and fastness to light.
Conventionally, artificial leather is used in various applications such as clothes, bags, shoes and interior materials, as a substitute for natural leather, or as a leather material having properties better than natural leather.
In order to obtain touch and feeling like natural leather, artificial leather is generally formed by appropriately selecting a resin layer comprising a polyurethane resin, such as a surface layer, a foamed layer or an adhesive layer, and laminating the resin layer on a substrate comprising a fibrous material (such as non-woven fabric, woven fabric or knitted fabric). A solvent type resin has mainly been used as the polyurethane resin. Recently, however, considering environmental problems, a technique of using a solventless resin is being studied.
For example, an example of artificial leather using a solventless resin includes a method of using a thermoplastic elastomer layer produced by a melt film-forming method as a resin layer comprising a polyurethane resin. Patent Document 1 discloses a laminate (artificial leather) having a porous layer containing bubbles, comprising a thermoplastic elastomer and produced by a melt film-forming method, on a surface of a fibrous substrate, and having a non-porous layer comprising a specific thermoplastic resin composition and produced by a melt film-forming method, on the porous layer, unevenness pattern or mirror pattern being present on the surface of the non-porous layer.
Other example of the artificial leather includes a method of using a solventless moisture-curing hot-melt polyurethane resin as a resin layer comprising a polyurethane resin. Patent Document 2 discloses a method of producing a polyurethane porous sheet-like structure (artificial leather) by heat-melting an isocyanate group-containing urethane prepolymer which is semi-solid or solid at ordinary temperatures, and a compound capable of reacting with an isocyanate group and/or a urethane curing catalyst, respectively, followed by stirring and mixing, and additionally introducing a gas, thereby performing mechanical foaming, applying or adhering the foamed material to a sheet-like material, and cooling to ordinary temperature.
Properties required in artificial leather include various items such as appearance very similar to natural leather, touch, soft feeling, peel strength, tear strength, abrasion resistance and flex durability at low temperature. Of those, abrasion resistance and flex durability at low temperature were difficult to be achieved simultaneously for the reason that requirements of a polyurethane resin satisfying those properties are contradictory.
The above-described conventional artificial leathers obtain the respective target effects, but did not simultaneously satisfy abrasion resistance and flex durability at low temperature.
Relevant prior art is:
    [Patent Document 1] JP-A 9-239886    [Patent Document 2] JP-A 2002-249534